Sekundärreglerad hydraulisk transmission i en sexhjulig skotare

Liselott EricsonLinköpings universitet

2

3

Soil damages

• Outdoor activities and recreation values• Biological effects• Damages which lead to reduced timber

production

4

5

Pendulum arms

Purpose• Even soil pressure• Increased comfort for

the operator• Reduced slip

6

The forwarder

7

Forwarder transmission

8

Primary controlSecondary units

• The primary unit controls the speed of the load

• The torque is the result of the load

Primary unit

9

p

eppref

Secondary control

Cp

Primary unit

Secondary units

• The primary unit controls the system pressure

• The secondary unit controls the torque or speed of the load

11

Cp

eppref

p

Speed control strategy

12

Speed control strategy

wref

C ,1w

w1

em,1

C ,2w

w2em,2

vref

13

Speed control strategy

em,1

C ,2w

w2

C ,1w

w1

wrefKinematicmodel wref,2

wref,1

em,2

vref

14

Torque control strategy

vref CT

vcurrent

wref,2wref,1

em,1 em,2

w1

Cs,1

w2

Cs,2

p

15

Summary

• Two control strategies is purposed– Speed control – differential lock with adjusted

wheel speed– Torque control – differential with slip counter

measure• Soil damage is supposed to be reduced by less

slip• Next step: Try and compare the strategies in

the forwarder